Motor vehicles are equipped with a windshield wiper device for cleaning or wiping a surface of a windshield. The windshield wiper device includes a wiper blade, a wiper arm and a wiper motor oscillating the wiper arm. The wiper blade is releasably coupled to the wiper arm. The wiper blade is placed on the surface of the windshield by the wiper arm. The wiper blade wipes the surface of the windshield while sliding thereon through oscillation motions of the wiper arm.
The wiper blade has an elongated wiper rubber and a frame structure. The wiper rubber is placed in contact with the windshield surface. The frame structure holds and supports the wiper rubber along its length. The frame structure may include an assembly having a main lever and a plurality of yoke levers linked to the main lever. The main lever is connected to the wiper arm. The yoke lever is linked to the main lever or another yoke lever at its middle. The yoke levers hold the wiper rubber.
When a motor vehicle runs, wind or air stream impinging against the windshield applies a force to the wiper blade along the entire length of the wiper blade placed on the windshield. The wiper blade generally stands upright on the surface of the inclined windshield. Thus, the force applied by the wind or air stream acts in a direction of lifting the wiper blade from the surface of the windshield. The faster the motor vehicle runs, the stronger such a lift force would be. This weakens the contact between the wiper rubber and the windshield surface, thus deteriorating wiping performance.
To address the deterioration in wiping performance caused by the lift of a wiper blade, it is known in the art to attach a spoiler to the wiper blade. The spoiler interacts with wind or air stream and thereby applies a force in a direction opposite to the lift of the wiper blade. By way of example, Korean Patent Application Publication No. 10-2003-0031158 discloses a wiper blade with a spoiler attached to a main lever. It is also disclosed in the art to attach a cover to a wiper blade so as to cover a main lever and a yoke lever. By way of another example, Korean Patent Application Publication No. 10-2006-0051763 discloses a wiper blade with such a cover.